Specific microenvironment lymphyascular niche in lymph nodes during tumor metastasis. Bone marrow vascular niche (left), comprising specialized sinusoidal endothelium of venous origin (purple), forms a microenvironment for colonization with and maintenance of hematopoietic stem cells (HSCs). In contrast, tumor‐associated lymphangiogenesis within lymph nodes has induced remarkable enlargement of lymphatic network (right, green) composed of sinusoidal lymphatic endothelium. This specific microenvironment ‘lymphvascular niche’ might contribute to serve as a sanctuary for residence and survival of metastatic cancer stem cells in lymph nodes. CSC, cancer stem cell.